The present invention relates to a method for manufacturing a semiconductor optical integrated device of a structure in which optical waveguides are directly interconnected.
In a semiconductor optical integrated device which has a semiconductor laser and a photodetector, optical modulator, or the like directly interconnected, a low-loss optical connection is needed for interconnecting various elements. In particular, what is called direct coupling which directly interconnects optical waveguides is excellent for low-loss, efficient connection of various elements.
However, it is very difficult to manufacture a semiconductor optical integrated device of good reproducibility without abnormal growth nor deterioration of the coupling efficiency between two optical waveguide layers.